The molecular functions of fatty acid binding proteins (FABPs) remain obscure nearly 35 years after their discovery. Recent studies with knock-out mice indicate that FABPs play critical roles in the development of the metabolic syndrome and certain cancers making them potential therapeutic targets for these diseases. Inhibition of fatty acid binding to FABPs should provide a useful method to investigate the molecular functions that underlie their observed effects on metabolism, but no inhibitors of FABP binding are currently available. To address this need, a high throughput screening (HTS) assay will be developed to discover inhibitors of FABP binding using ADI FAB, a fluorescently labeled FABP. The aims of this project are to (1) optimize the ADI FAB assay for HTS and (2) screen a small molecule library to validate the effectiveness of the assay for the identification of inhibitors of FABP binding. To accomplish these aims, conditions of the ADI FAB assay will be varied to optimize the Z'-factor, rapid secondary screens will be developed to identify optical artifacts that alter the observed fluorescence and to confirm binding to FABPs, and screening results will be assessed by quantitative determination of inhibitor / FABP binding affinities and membrane permeability. Effective inhibitors will be used in a follow-up research program to study the molecular functions of FABPs in lipid metabolism and could lead to the development of therapeutic agents for such diseases as insulin resistance, atherosclerosis, and certain forms of cancer.